LTE (Long Term Evolution) modulation and WCDMA (Wideband Code Division Multiple Access) are distinct transmission standards that must both adhere to the same specifications for harmonic distortions, and both are measured in the same bandwidth and have the same limits. In LTE modulation, resource blocks (RBs) may be assigned (activated) to increase the active transmission bandwidth. For example, an LTE channel structure is provided in 3GPP (3rd Generation Partnership Project) standard TS 36.521-1 V2.0.0 (2008-12).
When few resource blocks (less than 22 in one embodiment) are activated in an LTE modulation, then the peak power of the harmonic distortion is undesirably high. This condition may be described as a low activity condition, which has a relatively small number of active resource blocks. This condition may also be described as a low data rate condition.
The conventional solution in industry is to place lossy filters in the transmission path to filter out the undesired harmonic distortions, which occur during low activity conditions. Unfortunately, this conventional solution increases the circuit footprint, increases the circuit cost, and increases the power consumption (thus decreasing the maximum talk time for any battery dependent device). Further, the lossy filters constantly consume power, even though they are really only needed during low activity conditions.
Harmonic distortions may also interfere with GPS (global positioning systems), and prevent GPS from functioning properly.